Telephone system



Jan. 4 1927.

R- F. STEHLIK TELEPHONE SYSTEM Filed Dec. 23, 14922 i Buda 2 Sheets-Sheet 1 Jan. 4., 192,7. y R. F. s-LEHLIK TELEPHONE SYSTEM Filed Deo. 25. 1922 2 vSheets-Sheet oi" the calledl line, 'the cifnneeling up ol. test wiper 73 doesI not have any ellect and test relay S4 energizes immediately. Assuming, however, that the wipers of the linder F are not standing on the terminals ot' the calling line, but are standing on sorne other set otl terminals, which is usually the case, testl relay 84 is short-circuitedA by the` grounded potential encountered by test Wiper 73, and the Wipers ot the nder F arerotated step by step by the buzzer-like act-ion of stepping magnet 9st which is operated from the ground encountered on the busy Vtest contacts.

When the terminals 26-28, inclusive, 'ot the calling line are-reached, test Wiper Til encounters the ungrounded Contact` 2T, and te it relay 84 in the linder allotter Fil, being no longer short-circuited, energizes in series with stepping magnet 9-1- ot' the linder F. Stepping magnet 94 not energizing at this time on account 'ot the high resistance of test relay 84. Upon energizing, test relay Seli closes at armature 87 a circuit for stepping magnet 81 whichv is exclusive of the local interrupter contacts or' the stepping mag net. Stepping magnet S1, upon energizine ni-ierely moves its pawl (not shown) into engagement with the next notch in the associated Wiper driving ratchet Wheel but does notadvance the switch Wipers. As further result of the energization oi test relay S4, 1t closes a circuit tor cut-oli relay 83 at armature 90. Relay 9S, upon energizing, opens the circuit of line relay S2 al: armature 89. Line relay 82, however. beingl slowsacting, does not 't'all back immediately.

a still further result ot thc energization otl test relay 8in-a circuit is cloed for relay 95 ot' the finder F in multiple with relay 83 otl the linder allotter FA as Jfollows: Freni ground by Way ot' the wm'kingcontact or armature 9() and said arn'iature. wiper 93 and the bank Contact upon which it is; standing, spring ol hey K and its resting Contact, and relay 95 to battery. Upon energizing, relay 95 connects up the line Wipers 'TQ and TelA at alimatures 96 and 98, and at armature 9T disconnects test Wiper 73 t'roin the junction o'l` steinviing magnet 9-l and lest relay 8l. and connects it to ground. thereby closing a circuit lor cut-oli' relay 11- througlrtest wiper T3, test contact Q7, and armature 15 olf line relay 1B and its Working contact. Upon energizing. cut-oil' relay 11 disconnects ground Yl'rom the resting Contact ot' armature 15 at armature 19 so as to prevent test contact 2T from becoming grounded locally Whenl line relay 13 deenergizes subsequently: closes a locking circuit tor itselt' at armature 20; and at armatures 18 and 21 disconnects the Winding oi line relay 13 and ground from conductors 11Iand 12. respectively. Line relay now deenergizes; opens thc circuit of start relay 43 at armature 17; and

places a shunt around start relay l2 a arnnu ture 10, whereupon relays 4t2 and 43 deenergize and remove ground from start conductor 99 at armatures 49 and 50.

ln the connector C, line relay 102 energizes over the calling line in respomeV to the line conductors being connected up in the finder l? at armatures 96 and 98, and closes a circuit for release relay 103 at armature 116. Release relay 103, upon energizing, prepares the operating circuit at armature 119,' prepares a circuit tor switching relay 108 at armature 118; and at armature 11T places ground'on release trunk conductor 76, thereby establishing a holding' cire .it for holding relay 95 before the slowfacting line relay 82 ot' the finder allotter FA has had time to 'dee-nergize.

lhen line relay 92 or the linder allotter eifentually deenergizes, it separa es the Wipers 91 and 92 at armature 85, and at armature 86 opens the circuit ot test relay 94. Upon'deenA ',z'ng, test relay 94 removes ground at one pomtlrom release trunk conductor 7G at armature 90, leaving relay 95 of the linder F and relay 83 ot' the allotter FA energized by ground sent back by the eonivctor C over release trunk conductor 76. frs a Jfurther result or the deenergization ot test relay Sfl, it opens the circuit ot stepping magnet 81 at armature 87, whereupon stepping magnet S1 deenergizes and advances the Wipers 1r-93, inclusive, into engagement with the next set oli banl contacts.

ln case the iinder associated with the next set of bank contacts is busy, relay 83 does not deenergize and the Wipers 91-93, inclusive, do not stop there but are rotated step by step in search ot an idle lindcr bythe buzzerlike action of stepping magnet 81, which operates from ground picked up on the busy test contm'fts` by test wiper 93. When an idle linder is finally reached, relay 83 decuergizes and connects up line relay 82 again at armature S9 eo as to render line relay 82 operative lor the next call. Y

ill/'heu the culling Vsubscriber operates his calling device it'or the lirst digitin the dcsired number, the circuit oit line relay 102 is onened a corresponding number ol' times at the calling substation, and each linie line relay 10:2 deenergizes', il closes at its armature 115 a circuit t'or Vertical magnet 110, the circuit at the time ol the first/closure being as follows: from ground by way or' armature 116 and its resting` conact, armature 119 and its Working contact. contact o'l oli-normal spring 113 and said spring, rela;v 101, and vertical magnet to battery. lly the operation ot vertical magnet 11u. inc.

switch 'wipers 18% inclusive, are raised' opposite the level ot contacts in which the terminals of the desired line are located, Relay 10l 1s energized 1n series With vertical magnet 110 and, being slow-acting, retains its armature attracted tl'lroughout the vertical movement, thereby maintaining its own circuit and that ot' vertical magnet 110 1ntact after the olf-normal springs have shitted as they do upon the lirst vertical step. At the end ot the vertical n'iovement, series relay 101i deenergizes and transfers the operating circuit trom the vertical to the rotary magnet.

'When the calling subscriber operates his calling device in accordance with the second digit in the desired number, each of the resulting deenergizations ot' line relay 102 results in a circuit being closed for rotary magnet 111, the circuit of rotary magnet 111 at the first closure being as follows: from ground by Way ot armature 116 and its resting contact, armature 110 and its Worliing Contact, normally open oli-nor1nal contacts controlled by olf-normal spring 113, armature 120 and its resting contact, resting contact of amature 125 and said armature, armature 131 and its resting Contact, and rotary magnet 111 to battery. By the operation ot the rotary magnet, the wipers of the switch are rotated into engagement with the set or" contacts in the selected level in which the desired line terminates, which in this case is the set comprising contacts 13S-138, inclusive. Relay 107 energizes in multiple With rotary magnet 111 and, being slow-acting, is maintained energized during the entire rotary movement. Upon energizing, relay 107 disconnects test Wiper 1341 from the upper winding of switching relay 108 and connects it to busy relay 106 at armature 126, and at armature 127 places a shunt around armature 125 and its resting contact so as to guard its own circuit and that oli rotary magnet 111 from being opened prematurely by busy relay 106 in care that relay energizes due to test Wiper 134 passing over busy test contacts.

Assuming the called line to be busy, test contact 137 is grounded, and busy relay 106 is accordingly energized when the switch Wipers come to rest upon the desired set of contacts, and relay 107, upon deenergizing at the end ol the rotary movement, completes a locking circuit for busy relay 106 as 'liollowsz l'rom ground by Way of the working contact ot armature 118 and said armature. armature 124E and its Working contact` and the normally closed contacts controlled by armature 126 to battery by Way ot'r busy relay 106. Also, since busy relay 106 is energized, slow relay 107, upon falling back, opens its own circuit and that of stepping niagnet 111 trom the impulsing circuit so as to prevent any further operation ot the switch Wipers, and further operation of relay 107 in case the calling subscriber should again turnhis calling device. Busy.

relay 106 at its lower armature connects a lead from the busy signalling machine to the lower heavy talking conductor, thereby sending back the usual busy tone to the calling :uhscriber to inlorm himthat he cannot obtain the desired connection :tor the time being. Upon hearing this tone, the calling subscriber replaces his receiver, whereupon the partly restablished connection is released in the usual manner.

Assuming now that the called line is idle when called as hereinbeifore described, test contact 137 is not grounded and busy relay 106 is consequently not energized when the switch Wipers come to rest on the terminals of the desired line, and slo\v-acting relay 107, upon deenergizing, completes 'a circuit for switching relay 108 in series with cut-otta relay 139 olf the called line circuit LC at armature 126 as follows: from ground by Way ot the Working contact ot armature 118 and said armature, arn'rature 124 and its resting contact, upper' Winding ol switching relay 108, resting contact ot' armature 126 and said armature, test Wiper 134, test .contact 137, and cut-olii relay 139 to battery. Upon energizing, cut-ofi' relay 159 disconnects the normal battery and ground connections otthe called line at its upper and lower armatures.

In the connector C, switching relay 108, upon energizing, liret closes a locking cir-V cuit or itself at its lightly adjusted armature 130, and then places ground directly on test Wiper 134 at armature 129; disconnects rotary magnet 111 and slow-acting relay 107 at armature 181; and at armatures 128 and 182 connects'up the line Wipers, whereupon ringing current is intermittently projected out over the called line to ring the br'dged bell at the called substation.

lfvlhen the called subscriber responds to the ringing of his bell by removing his receiver, a direct current circuit is closed over his line conductors for the upper Winding of ring-cut-of'f relay 105 of the connector C. Ring-cut-olf relay 105, upon energizing, lirst closes a locking circuit for itself at its lightly adjusted armature 122, and then disconnects the line Wipers from its own upper Winding and the source of ringing current and extends them to the windings of backbridge relay 101. ll hen this occurs, backbridge relay 101 energizes over the called line, and reverses the incoming conductors 75 and 77 as regards their connection with the windings of line relay 102, thereby reversing the direction of current flow in the calling subscribers loop. This operation does not have any particular function in the present case, but is used in other cases tor operating meters and the like.y The calling and called subscribers may now converse with each other as desired, the talking eircuit being outlined by the heavy conductors.

iWhen the conversation is terminated, the

two subscribers replace their receivers, and when the r ce'iver is replaced at substation A', back-bridge relay 101 of the connector C deenergizes and reverses the current flow in the calling line to normal.

When the receiver is replaced at the calling substation, the circuit ot line relay 102 is opened. Upon deenergizing, line relay 102 opens the circuit of release relay 103 at armature 116. Slow-acting release relay 103, upon deenergizing in response to the prolonged opening of its circuit at this time, removes ground trom the upper terminal ot' the upper winding ot switching relay 108 at armature 118, removes ground trom release trunk conductor 76 at armature 117, and at armature 119 closes a circuit for release magnet 109 by Way ot' off-normal contacts 112. Upon the energization of release magnet 109, the shaft and Wipers ot the connector C are restored to normal position in the usual manner, the circuit ot release magnet 109 being opened at off-normal contacts 112 by the switch shalft when the .latter reaches normal position.

In the iind'er F, the removal ot the ground potential t'rom release trunk conductor 76 renders the iinder F selectable to the iinder allotter FA again and opens the circuit 0f relay 95. Relay 95, upon deenergiZinO', removes ground't'rom test Wiper 7 3 at armature 97, and at armatures 96 and 98 disconnects its line Wipers.

Cut-oit relay 14 lot the line circuit LC now deenergizes in response to the opening of its circuit by relay 95 ot the tinder F; opens a point in its previously established locking circuit at armature 20; replaces ground on test contact 27 at armature 19; and at armatures 18 and 21 connects up the calling bridge again.

1t may happen occasionally that a calling subscriber makes a call, and start relays 42 and 43 energize to place ground on the start conductor 99 through relay 44, but the starting circuit is open, tor example, at armature 59 and its resting contact or at armature 89and its resting contact. When this occurs, relay 44 is not energized and a circuit is closed through armature 51 and its resting contact for the lamp L to bat-- tery through the common pilot relay 49. Relay 49, upon energizing, closes a circuit. for the alarm buzzer 50, thereby attracting the attention ot' an attendant who may take such steps as he deems necessary to clear up the. trouble.

It may happen occasionally that the chain circuit which shunts starting relay 42 is opened and the circuit li'or starting relay is not closed. This may happen due to the shunting chain circuit otl relay 42 being opened accidentally due, for example, to dirty contacts, Aor itmay happen, when the chain circuitris opened in the usual manner when a subscriber makes a call, on account ot the tact that a contact such as armature 17 and its Working contact is dirty or badly adjusted and, therefore, does not close the circuit of relay 43. However, regardless ot the cause for the above named condition exist-ing, a finder is started in the usual manner in response to the grounding of the start conductor at armature 49, but, since relay 43 is d'eencrgized, a circuit is closed through armature 50 and its restingcontact 'for relay Upon energizing, relay. disconnects test contact ot a dead set comprising contacts 223-25, inclusive, trom ground, and connects it to relay 46 through armature 54 and its resting Contact.

1t Will be assumed now that the above named condition exists because a subscriber is making a call and the Contact on his line relay tails to close the circuit ot relay 43. 1t will be assumed further that the finder allotted in this case is the linder F, and that the -Wipers o'l' the tinder F pass over the contacts 23-25, inclusive, before they come into engagement with the contacts ot the calling line. rfhat being the case, When the Wipers 72-74, inclusive, arrive on the contacts 23-25, inclusive, a circuit is closed for relay 46 ot the relay group RG as follows: from ground by Way ot' vthe Working contact Ot armature 49 and said arma-ture, armature 50 and its resting contact, relay 46, resting contact oft armature 54 and said armature, Working contact ot armature 52 and said armature, test contact 24, test Wiper 73, armature 97 and its resting contact, Wiper 92, Working contact ot armature 85 and said armature, Wiper 91, and rotary magnet 94 to battery. Relay 46, upon energizing over this circuit, connects up the marginal relay 47 at armature 53 in multiple With rotary magnet 94. Relay 47 does not energize in multiple with magnet 94 owing to its marginal adjustment, and to the reduction in potential due to the relative values ot' the resistances otl relay 46 and stepping magnet 94. rlest relay 84 in the inder allotter FA, Fig. 1, does not energize at this time in multiple with relay 46 ot' the relay group RG owing to its oWn still adjustment and to the relatively 10W resistance of relay 46.

rlihe resistance ot relay 46 is ot such a value that While it appreciably slows up the energization ot' stepping magnet 94 0I" the finder F, it does not prevent magnet 94 from yenergizing and, consequently, the `vipers oi" the .tinder F are not stopped on the contacts 23-25, inclusive. but are rotated on in search of the calling line.

Vhen Wiper 73 passes ott' test contact 24, the shunt ot stepping magnet 94 is removed from around relay 47 in the relay group RG, whereupon relay 47 energizes in series With relay 46 through armature 53 andits Working contact, and at armature 54 disconnects test contact 24 from the junction of its own winding and that of relay 46, and connects it to the upper winding of relay 48 for a purpose which will be explained fully hereinafter.

Vhen the finder F reaches the terminals of the calling line, the calling line relay deenergizes in the hereinbefore described manner and yreplaces the shunt around relay 42, whereupon relay 42 deenergizes and opens the circuit of relays 45-47, inclusive. rFliese relays then deenergize with results which are apparent.

It will be assumed now that the chain circuit which keeps relay 42 normally shunted has become open accidentally at a time when noy line is calling; that a finder is started, the nder F, for example, in the usual manner; and that relays 46 and 47 are energized as hereinbefore described in response to the wipers of the finder F passing over the set of contacts 23-25, inclusive. Under these conditions, no calling line is found and the wipers of the finderr F continue to rotate until they come into engagement with the contacts 28-25, inclusive, the second time. `When this occurs, relay 48 is energized by means of its upper winding over a circuit which includes the working contact of armature 54 and said armature, and the previously traced circuit to battery including stepping magnet 94. The resistance of the upper Winding of relay 48 is sufficiently high to prevent stepping magnet 94 from operating in series with it, but is not high enough to allow the marginally adjusted switching relay 84 to energize inmultiple with it. pon energizing, relay 48 closes a locking circuit for itself at armature 56; opens a point in the circuit of the signal lamp L and pre pares a circuit for the signal lamp L at armature 57; and at armature 59 opens the start conductor. Vhen this occurs, yline relay 82 of the finder allotter FA deenergizes; disconnects test relay 84 at armature 8G; and at armature 85 disconnects the unction of test relay 84 and stepping magnet 94A from test wiper' 7 3 ofthe finder F, thereby opening the circuitof the upper winding of relay 48, leaving relay 48 energized by means i of its lower winding.

In the Vrelay group RG, as a result of the opening of tliesstarting circuit at armature 59 of relay 48, relay 44 deenergizes and. cornpletes a circuit for the signal lamp L as fol-4 lows: from ground by way of the working contact of armature 49 and said armature, armature 51 and its resting Contact, armature 57 and its working contact, the lamp L, and pilot relay 49 to battery. The lamp L now becomes lighted to inform the attendant of the nature of the trouble` and the pilot relay 49, upon energizing, closes a circuit for the buzzer 50 to attract the attention of the attendant.

In case a call is made before the attendant has responded to the alarm, the equipment is not in any way tied up, and the finder F starts hunting lfor the calling line in the usual manner, for the reason that relay 43,'

on energizing, when the call is made, opens the circuit of relays 45-48, inclusive, whereupon these relays deenergize and the start wire is connected up again at armature 59 and its resting contact. The finder F auto matically steps off the contacts 22E-5, inclusive, on account of the fact that relay 45 of the relay group RG, on deenergizing, grounds test contact 24 again at armature 52.

I/Vhen the call is taken care of and the finder allotter FA allots the next finder, the start conductor remains grounded owing to the factthat relay 42 is still unshunted and the allotted finder repeats the process described above with the result that the lamp L is again lighted to inform the attendant of the trouble.

It will be seen from the foregoing description of the starting arrangement and of the trouble indicating signals that a very efficient starting arrangement has been'provided; that the attendant is signalled in case the start wire itself is open; and that the attendant is signalled eventually in case the chain starting circuit is opened accidentally.

Perhaps in concluding it will be well to sum up certain parts of the foregoing description'by stating that two start relays are provided instead of one as heretofore. One start relay has its circuit normally closed, but is shunted by a chain circuit including normally closed contacts in series on all the line relays. This start relay 'can be 'depended upon absolutely to energize whenever a call is made.v However, this relay some times energizes due to an accidental opening of its shunting chain circuit and starts a finder when no line .is calling. The arrangements above described are made for then stopping the nder to prevent excessive wear. The first starting relay having been rendered ineffective, the second start relay comes into play to restart the finder when a call is actually made. This other starting relay, although perhaps not quite so reliable as the normally shunted relay, is energized in a standard circuit, nevertheless, and affords an keffective means of startingv finders pending the repair of the trouble in thc other starting circuit.

Vilhat is claimed is:

l. In a telephone system, telephone lines, a plurality of finders, a circuit for starting an idle oneof said finders in search of a calling one of said lines, a signalling circuit, means for closing said circuits at the same time,`

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rality of finders, a circuit for starting an idle one of said finders in search of a calling.

line is calling to open its normally closed contacts and to close its normally open contacts, and'means for closing said starting circuit responsive to either the opening'of said normally closed contacts or the closure of said normally open contacts.

In a finder system, a normally closed starting circuit, means responsive t-o any opening` of' said circuit for starting a finder, and means for stopping the started finder and signalling an attendant when said-circuit is opened due to some canse other than the initiation o'f a call.

fl. In a telephone system, telephone lines, a plurality of nder switches having wipers for findingV the calling ones of said lines, an allotter for allotting said finders for use, a magnetl in each of said `finders for bringing about the movement of the associated wipers, a circuit for each magnet including a wiper of the associatednder, and a` relay in said allotter for closing the circuits of said magnets.

5. In a telephone system, telephone lines, a plurality of finders for finding the calling. ones of said lines, an allotter. for allotting said finders .for use, anda test relay in said allotter, a circuit for said relay over which it individually tests the lines searched over by an allotted finder.

6. In a telephone system, subscribers lines, a group of finders for extending said lines when calling, magnets in--saidifinders a .test relay common to all of said finders, and means for associating saidrelay withsaid finderssuccessively, a circuit for said relay including the magnet ,ofV said associated finder in series over which said relay is energized to control said magnet.

7. In a telephone syst-em, subscribers. lines, a group offinders for extending said lines when calling, a test relay commonY to. all of said finders, a test wiperfor each finder, and means forconnect-ing said test relay to said Wipers in turn as the several finders are taken `for use.

8. In a telephone system, subscribers lines, a group of finders for extending said lines when calling, motor magnets in said finders a testrelayy common to all of said finders, an auxilliary switch for selecting idle finders one at a time and for connecting said test relays thereto in a circuit including said motor magnet, and means in said switch for restricting said test relay to the use of any finder selected.

9. In a telephoneA system, subscribers lines, a grou-p of finders for extending said lines when calling, motor magnets for said finders, a common line relay anda common test relay for controlling all said motormag nets, and means for connecting said test recircuit controlled `by said line relay thereby enabling said relays to control said magnets separately.

l0. In a telephone system, subscribers lines, a group of finders ior extendingsaid lines when calling, motor magnets for said finders, a common line relay, a common test relay, an auxiliary switch for associating said relays with said finders one at1 a time, said test relay being in series with the motor magnet cf the selected finder, and circuits for enabling said line relay. to close the motor magnet circuit of any finder with which it is associated, and vmeanssubsequently controlled by said test relay for opening the circuit of said motor magnet.

ll. In a telephoneA system, telephone lines, a plurality of finders, a circuit for starting an idle one ofsaidfinders in searchofa calling-one ofsaid lines, a signal, means for closing said starting circuit at' one point, and means responsive to the closing-,of said circuit for operating said signal in case said stai-ting circuit is open at another point, the last-named means including a relay in series with said `starting circuit.

l2. In a telephone system, subscribers lines, a group of finders for extending-said lines when calling, magnets in saidffinders, a test relay common to all' said finders, a test wiper for each finder, and means for connecting said test relay to said Wipers and said magnets as the several finders are taken for use.

13. In a telephone system, telephone lines, a group of finder switches having wipers, a magnet inV each switch', an allotter for allotting said .finders for use, a test relay common to said finders, means responsive to the initiation of' a call from one of: said lines for connecting said test relay in a circuitincluding the motor magnet of the allotted finder, and means for shunting said relay and vfor completing Van energizing circuit for said magnet which operates to drive said wipers in search of said lcalling line.

lef. In a telephonesystem, a group of finders having wipers, telephone lines accessible to said wipers, motor magnets in said vfinders for driving said wipers, a test relay common to said finders, means for al1 lotting said finders for use one at a time and for preparing a circuit for saidtest relay in series with said motor magnet, and means responsive fo the initiation ofthe callby one of said vlines for completingsaid circuit and for short circuiting said test relay until said wipers are associated with said calling line.

l5. In a telephone system, a group of finders having wipers including a test wiper,

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telephone lines terminatingl in Contacts accessible to said Wipers, motor magnets in said linders for driving said Wipers, a test relay common to said finders, an allotter for allotting said finders for use one at a time and for preparing a circuit for said test relay in series with said motor 1nagne't,-means responsive to the initiation of a call by one of said lines for removing ground from an associated Contact to mark that line Calling, means for then completing said eireuit to operate said magnet` and for short circuiting said testv relay through said test Wiper, and means operated by the energization or said test relay when said test Wiper iinds said marked Contact for controlling said iinder.

16. In a finder system, a plurality of finders having banks of contacts over which Wipers are driven in Search of a Calling line, a normally closed starting Circuit for said linders, means responsive to any opening of said circuit for starting a finder, an arresting Contact set in said bank, means responsive to the lirst engagement of said Wipers with said Contact set for preparing a nder stop Circuit, means responsive to a second engagement of said Wipers with said Contact set for completing said stop circuit to stop said inder Wipers on said arresting contacts, a signal, and means operated by the closure or' said stop circuit for operating sain signal.

1n Witness whereof, I hereunto subscribe my name this 20th dayof December, A. D., 1922.

RUDOLPH F. STEHLK 

